Context data in upnp service information

ABSTRACT

A system, device, and method provide for the selection of a device to perform a service using context information for the device. The context information may be included in a request from a control point device to the device or may be included in a response from the device to the control point device. The context information provides additional information relative to the services provided by the device or relative to the device itself. For example, if the device is a camera, the camera may include for each photograph taken by the camera a date the photograph is taken, a time the photograph is taken, a location at which the photograph is taken, a subject matter of the photograph, a temperature at the photograph location, a photographer, etc in the context information. Additionally, the camera may include the current geographic location of the camera in the context information.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a Divisional of U.S. patent application Ser. No.10/922,417 entitled “CONTEXT DATA IN UPNP SERVICE INFORMATION” filedAug. 20, 2004, and is incorporated herein in its entirety as if setforth in full.

FIELD OF THE INVENTION

The present invention is related to networks. More particularly, thepresent invention relates to resource discovery in a UPNP environmentusing context information.

BACKGROUND OF THE INVENTION

Universal Plug and Play (UPnP™) defines an architecture for the networkconnectivity of intelligent consumer electronics, wireless devices,printers, and PCs of all form factors. The goal of UPnP technology is toprovide easy-to-use, flexible, standards-based connectivity for ad-hocor unmanaged networks whether in a home, in a small business, or inpublic spaces. In support of this goal, UPnP supportszero-configuration, “invisible” networking, and the automatic discoveryof devices from a wide range of manufacturers. As a result, a device candynamically join a network, obtain an IP address, convey itscapabilities to the network, and determine the presence and capabilitiesof other devices. UPnP also provides a consistent, interoperableframework for remote Internet Gateway Device (IGD) configuration andmanagement. UPnP is built using Hypertext Transfer Protocol (HTTP) overthe User Datagram Protocol/Internet Protocol (UDP/IP) or theTransmission Control Protocol/Internet Protocol (TCP/IP) in addition tothe eXtensible Markup Language (XML). HTTPU and HTTPMU are variants ofHTTP defined to deliver messages over UDP/IP instead of TCP/IP.

Devices on a UPnP network can be connected using any communication mediaincluding Radio Frequency wireless (including Radio FrequencyIDentification (RFID)), phone line, power line, IrDA, Ethernet, andInstitute of Electrical and Electronics Engineers (IEEE) 1394. Thus, anycommunication medium that can be used to network devices can enableUPnP.

UPnP is an open networking architecture that consists of services,devices, and control points. Services are groups of states and actions.For example, a light switch has an “on” state and an “off” state. Anaction allows the network to determine the state of the switch or tochange the state of the switch and is a command that can be used totrigger services to perform a function. Services typically reside indevices and provide device functionality that can be controlled usingcontrol points. A device may be a physical device such as a camcorder ora logical device such as a computer that is performing the functions ofa camcorder. Devices may be physical or logical entities and arespecified using simple XML descriptions and containing ApplicationProgramming Interfaces (APIs) for providing services. Physical devicesmay host multiple logical devices, and each device may host multipleservices. Control points are software applications that retrieve UPnPservice and device descriptions, that send actions to services, and thatreceive events from services. A control point is capable of discoveringand controlling other devices. An event is a message from a device to acontrol point that is used to keep subscribed control points informed ofdevice status. A UPnP device may be a container for services and nesteddevices. For example, a combination TV/DVD player provides services andincludes a nested device that may be the DVD player, for example.

Messages are transported over UPnP networks using HTTP over the UDP/IPor TCP/IP. The supported message formats are Simple Service DiscoveryProtocol (SSDP), General Event Notification Architecture (GENA), andSimple Object Access Protocol (SOAP). UPnP relies on these threeprotocols to enable networking without a classical networkadministrator. SSDP provides for the discovery of devices on thenetwork. GENA provides for subscribing to event reports and for thepublication of those events. SOAP provides for control of the networkdevices through remote procedure calls between control points anddevices. Required UPnP information is inserted into all messages beforethey are formatted using SSDP, GENA, and SOAP and delivered via HTTP,HTTPU, or HTTPMU.

Given an IP address, the first step in UPnP networking is discovery. Thediscovery process for a UPnP device includes advertisement of the devicepresence on the network to other devices and control points using SSDP.Thus, when a device is added to a network, the device advertises itsservices to the control points on the network. Similarly, a new controlpoint discovers UPnP devices on a network using SSDP. If an SSDP servicehears a discovery request that matches a service that it offers then theservice responds to the control point. Thus, UPnP allows a control pointto search for devices of interest on the network.

The information exchanged between the device and the control point inboth cases is a discovery message that provide basic information aboutthe devices or one of its services, and a description Uniform ResourceLocator (URL) that can be used to gather additional detailed informationabout the device. XML is used to describe the device features andcapabilities. The notification announcement message URL points to an XMLfile in the network that contains a description of the UPnP device'scapability. Thus, by retrieving the XML file, other devices can evaluatethe features of the device and determine if the features satisfy theirrequirements. Thus, after a control point discovers a device, thecontrol point retrieves the device's service description from the URLprovided by the device in the discovery message. The UPnP descriptionfor a device includes a list of any embedded devices or service, as wellas URLs for control, for eventing, and for presentation.

The UPnP description for a service includes a list of actions theservice responds to and a list of variables that model the state of theservice. The service publishes updates when these variables change bysending event messages. A control point may subscribe to thisinformation so that it automatically receives the updates. Eventmessages contain the names of one of more state variables and thecurrent value of those variables. These messages are also expressed inXML and formatted using GENA. Thus, after retrieving the description ofthe device, the control point can send actions to a device's service bysending a suitable control message to the control URL for the service.

Control messages are also expressed in XML using SOAP. In response tothe control message, the service returns any action-specific values.Additionally, if a device has a URL for presentation, the control pointcan retrieve a page from this URL, load the page into a browser, anddepending on the capabilities of the page, allow a user to control thedevice and/or view device status. Each UPnP control request is a SOAPmessage that contains the action to invoke along with a set ofparameters. The response is a soap message as well and contains thestatus, return value, and any return parameters. The control point canrefine the search to find only devices of a particular type, thatperform particular services, or a specific device. The control point cannot, however, refine the search based on context information. Contextinformation includes additional information about the device and theservices that the device is capable of providing. For example, thecontext information may include the current geographic location of thedevice. Context information may include the device availability forexample if the device is a printer or a facsimile machine.

What is needed, therefore, is a method of including context informationto refine a search for a device or a search for an item at a device in aUPnP environment. What is further needed is a method of including theexistence of context information to refine a search for a device in aUPnP environment.

SUMMARY OF THE INVENTION

An exemplary embodiment of the invention relates to a device forperforming a service for a second device. The device includes, but isnot limited to, a memory, a communication interface, and a processor.The memory stores a device service description, wherein the deviceservice description includes context information of the device. Thecommunication interface is configured to receive a request sent from afirst device using a network, the request to retrieve the device servicedescription, and to send a response to the first device using thenetwork, the response including the device service description. Theprocessor couples to the communication interface and to the memory andis configured to select the device service description from the memoryand to create the response including the device service description.

A format of the response may be, but is not limited to, a Simple ServiceDiscovery Protocol and a Simple Object Access Protocol. A format of therequest may be, but is not limited to, a Simple Service DiscoveryProtocol and a Simple Object Access Protocol. The context informationmay include, but is not limited to, a geographic location of the device.

Another exemplary embodiment of the invention relates to a device forselecting another device to perform a service. The device includes, butis not limited to, a communication interface and a processor. Thecommunication interface is configured to send a first request to a firstdevice using a network, the first request to retrieve a first deviceservice description from the first device, the first device servicedescription including context information of the first device, and toreceive a first response from the first device using the network, thefirst response including the first device service description. Theprocessor couples to the communication interface and is configured toselect the first device to perform a first service for the device basedon the context information of the first device included in the firstdevice service description.

A format of the response may be, but is not limited to, a Simple ServiceDiscovery Protocol and a Simple Object Access Protocol. A format of therequest may be, but is not limited to, a Simple Service DiscoveryProtocol and a Simple Object Access Protocol. The context informationmay include, but is not limited to, a geographic location of the device.

The processor may be further configured to determine a geographiclocation of the device, to determine a pointing direction to the firstdevice from the device, and to identify the first device based on thepointing direction to the first device from the device, the geographiclocation of the first device, and the geographic location of the device.The communication interface may be further configured to send a secondrequest to a second device using the network, the second request toretrieve a second device service description from the second device, thesecond device service description including context information of thesecond device, and to receive a second response from the second deviceusing the network, the second response including the second deviceservice description. The processor may be further configured to selectthe second device to perform a second service related to the firstservice for the device based on the context information of the seconddevice included in the second device service description. The contextinformation of the second device may include, but is not limited to, ageographic location of the second device. The processor may be furtherconfigured to determine a pointing direction to the second device fromthe device and to identify the second device based on the pointingdirection to the second device from the device, the geographic locationof the second device, and the geographic location of the device.

Another exemplary embodiment of the invention relates to a system forselecting a device to perform a service. The system includes, but is notlimited to, a first device and a second device. The first deviceincludes, but is not limited to, a memory, a first communicationinterface, and a first processor. The memory stores a first deviceservice description wherein the first device service descriptionincludes context information of the first device. The firstcommunication interface is configured to receive a first request from asecond device using a network, the first request to retrieve the firstdevice service description from the first device, and to send a firstresponse to the second device using the network, the first responseincluding the first device service description. The first processorcouples to the first communication interface and to the memory and isconfigured to select the first device service description from the firstmemory and to create the first response including the first deviceservice description.

The second device includes, but is not limited to, a secondcommunication interface and a second processor. The second communicationinterface is configured to send the first request to retrieve the firstdevice service description from the first device and to receive thefirst response from the first device. The second processor couples tothe second communication interface and is configured to select the firstdevice to perform a first service for the second device based on thecontext information of the first device included in the first deviceservice description.

Another exemplary embodiment of the invention relates to a method ofselecting a device to perform a service. The method includes, but is notlimited to, retrieving a first device service description from a firstdevice using a network, the first device service description includingcontext information of the first device, and selecting the first deviceto perform a first service for a second device based on the contextinformation of the first device included in the first device servicedescription.

The context information of the first device may include, but is notlimited to, a geographic location of the first device. Selecting thefirst device to perform the first service for the second device mayinclude, but is not limited to, pointing the second device at the firstdevice, determining a geographic location of the second device,determining a pointing direction to the first device from the seconddevice, and selecting the first device based on the pointing directionto the first device from the second device, the geographic location ofthe first device, and the geographic location of the second device.

The method may further include retrieving a second device servicedescription from a third device using the network, the second deviceservice description including context information of the third device,and selecting the third device to perform a second service related tothe first service for the second device based on the context informationof the third device included in the second device service description.

The context information of the third device may include, but is notlimited to, a geographic location of the third device. Selecting thethird device to perform the second service for the second device mayinclude, but is not limited to, pointing the second device at the thirddevice, determining a pointing direction to the third device from thesecond device, and identifying the third device based on the pointingdirection to the third device from the second device, the geographiclocation of the third device, and the geographic location of the seconddevice.

The method may further include selecting an item in a display at thesecond device while pointing the second device at the first device andreleasing the item in the display at the second device while pointingthe second device at the third device, thereby copying the item from thefirst device to the third device.

Another exemplary embodiment of the invention relates to a computerprogram product for selecting a device to perform a service, thecomputer program product includes, but is not limited to, computer codeconfigured to retrieve a first device service description from a firstdevice using a network, the first device service description includingcontext information of the first device, and to select the first deviceto perform a first service for a second device based on the contextinformation of the first device included in the first device servicedescription.

Another exemplary embodiment of the invention relates to a device forperforming a service for a second device. The device includes, but isnot limited to, a communication interface and a processor. Thecommunication interface is configured to receive a request sent from afirst device using a network, the request to perform a service at thedevice, and the request including context information associated withthe service, and to send a response to the first device using thenetwork. The processor couples to the communication interface and isconfigured to perform the service based on the context information.

Another exemplary embodiment of the invention relates to a device forrequesting a service from another device. The device includes, but isnot limited to, a communication interface and a processor. Thecommunication interface is configured to send a request using a networkto a first device, the request to perform a service at the first device,and the request including context information associated with theservice, and to receive a response from the first device. The processorcouples to the communication interface and is configured to create therequest including the context information.

Another exemplary embodiment of the invention relates to a system forrequesting a service from another device. The system includes, but isnot limited to, a first device and a second device. The first deviceincludes, but is not limited to, a first communication interface and afirst processor. The first communication interface is configured toreceive a request sent from a second device using a network, the requestto perform a service at the first device, and the request includingcontext information associated with the service, and to send a responseto the second device using the network. The first processor couples tothe first communication interface and is configured to perform theservice based on the context information. The second device includes,but is not limited to, a second communication interface and a secondprocessor. The second communication interface is configured to send therequest using the network to the first device, and to receive theresponse to the request from the first device. The second processorcouples to the second communication interface and is configured tocreate the request including the context information.

Another exemplary embodiment of the invention relates to a method forrequesting a service from another device. The method includes, but isnot limited to, creating a request, the request to perform a service ata first device, and the request including context information associatedwith the service, sending the request using a network to the firstdevice, and receiving a response to the request from the first device.

Another exemplary embodiment of the invention relates to a computerprogram product for requesting a service from another device. Thecomputer program product includes, but is not limited to, computer codeconfigured to create a request, the request to perform a service at afirst device, and the request including context information associatedwith the service, to send the request using a network to the firstdevice, and to receive a response to the request from the first device.

Another exemplary embodiment of the invention relates to a device forperforming a service for a second device. The device includes, but isnot limited to, a communication interface and a processor. Thecommunication interface is configured to receive a request sent from afirst device using a network, the request to perform a service at thedevice, and to send a response to the first device using the network,the response including context information associated with the service.The processor couples to the communication interface and is configuredto create the response including the context information and to performthe service.

Another exemplary embodiment of the invention relates to a device forrequesting a service from another device. The device includes, but isnot limited to, a communication interface and a processor. Thecommunication interface is configured to send a request using a networkto a first device, the request to perform a service at the first device,and to receive a response from the first device, the response includingcontext information associated with the service. The processor couplesto the communication interface and is configured to create the request.

Another exemplary embodiment of the invention relates to a system forrequesting a service from another device. The system includes, but isnot limited to, a first device and a second device. The first deviceincludes, but is not limited to, a first communication interface and afirst processor. The first communication interface is configured toreceive a request sent from a second device using a network, the requestto perform a service at the first device, and to send a response to thesecond device using the network, the response including contextinformation associated with the service. The first processor couples tothe first communication interface and is configured to create theresponse including the context information and to perform the service.The second device includes, but is not limited to, a secondcommunication interface and a second processor. The second communicationinterface is configured to send the request using the network to thefirst device, the request to perform the service at the first device,and to receive a response from the first device. The second processorcouples to the second communication interface and is configured tocreate the request.

Another exemplary embodiment of the invention relates to a method forrequesting a service from another device. The method includes, but isnot limited to, creating a request, the request to perform a service ata first device, sending the request using a network to the first device,and receiving a response to the request from the first device, theresponse including context information associated with the service.

Another exemplary embodiment of the invention relates to a computerprogram product for requesting a service from another device. Thecomputer program product includes, but is not limited to, computer codeconfigured to create a request, the request to perform a service at afirst device, to send the request using a network to the first device,and to receive a response to the request from the first device, theresponse including context information associated with the service.

Other principal features and advantages of the invention will becomeapparent to those skilled in the art upon review of the followingdrawings, the detailed description, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiments will hereafter be described with reference tothe accompanying drawings, wherein like numerals will denote likeelements.

FIG. 1 is an overview diagram of a system in accordance with anexemplary embodiment.

FIG. 2 is a block diagram of a first device in accordance with anexemplary embodiment.

FIG. 3 is a block diagram of a second device in accordance with anexemplary embodiment.

FIG. 4 is an overview diagram of a message sequence in accordance withan exemplary embodiment.

FIG. 5 is an overview diagram of a sample use case in accordance with anexemplary embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The term “device” as used herein includes a variety of network nodes.Such network nodes include printers, workstations, servers (for example,printer servers or file servers), scanners, PCs of all form factors,intelligent appliances (for example, cameras, video cameras, TVs, DVDplayers, radios), etc. The devices communicate over a network usingcommunication protocols such as, for example, TCP/IP and UDP/IP. Adevice advertises its ability to perform a service and may be controlledby another device denoted a control point as related previously. Thecontrol point listens or searches for devices that it is capable ofcontrolling to identify and to select devices to perform services forthe control point. The device advertises its services possibly throughan address to a page written in XML format. The XML formatted fileincludes information about the device and the services that the devicemay provide and is denoted a device service description. The XMLformatted file may also include the address to additional informationrelating to the services advertised by and provided by the device. Theadditional information may also be captured in an XML formatted file.The control point may issue simple HTTP Get Requests to retrieve thedevice service description. The device may respond with an HTTP GetResponse that includes the device service description. Using thisdescription, the control point may select the device to perform aparticular service for the control point.

With reference to FIG. 1, the system 2 comprises a network 4. Thenetwork 4 includes a plurality of devices 24. The plurality of devices24 may comprise a cellular telephone 6, an Integrated CommunicationDevice (ICD) 8, a Personal Data Assistant (PDA) 10, a PC 12 of any formfactor including a laptop 14, a printer 16, a scanner 18, a TV 20, avideo camera 22, etc. The devices 24 may communicate using varioustransmission technologies including, but not limited to, Code DivisionMultiple Access (CDMA), Global System for Mobile Communications (GSM),Universal Mobile Telecommunications System (UMTS), Time DivisionMultiple Access (TDMA), TCP/IP, UDP/IP, Short Messaging Service,Multimedia Messaging Service, e-mail, Instant Messaging, Bluetooth, IEEE802.11, etc. The devices 24 may communicate using various mediaincluding, but not limited to, radio, infrared, laser, cable connection,etc. The network 4 may include additional devices 24. Some or all of thedevices 24 of system 2 may comprise a control point device 26. Thesystem 2 may comprise any combination of wired or wireless networksincluding, but not limited to, a cellular telephone network, a wirelessLocal Area Network (LAN), a Bluetooth personal area network, an EthernetLAN, token ring LAN, a wide area network, the Internet, etc. The system2 may include both wired and wireless devices.

Communication between devices 24, 26 may be through one or more of thefollowing connection methods without limitation: a link establishedaccording to the Bluetooth Standards and Protocols, an infraredcommunications link, a wireless communications link, a cellular networklink, a physical serial connection, a physical parallel connection, alink established according to TCP/IP, etc.

With reference to FIG. 2, the device 24 comprises a display 30, acommunication interface 32, a processor 34, a memory 36, and a deviceservice description 38. Different and additional components may beincorporated into the device 24. The display 30 of the device 24 isoptional. The display 30 presents information to a user. The display 30may be a thin film transistor (TFT) display, a light emitting diode(LED) display, a Liquid Crystal Display (LCD), or any of a variety ofdifferent displays known to those skilled in the art.

The communication interface 32 provides an interface for receiving andtransmitting calls, messages, and any other information communicablebetween devices. Communications between the device 24 and other devices24, and/or to the control point device 26 may be through one or more ofthe following connection methods, without limitation: an infraredcommunications link, a radio frequency communication link, a wirelesscommunications link, a cellular network link, a link establishedaccording to TCP/IP, etc. Transferring content to and from the devicemay be through one or more of these connection methods. The device 24may communicate using various transmission technologies including, butnot limited to, CDMA, GSM, UMTS, TDMA, TCP/IP, Bluetooth, IrDA, RFID,etc. The device 24 may communicate using various media including, butnot limited to, radio, infrared, laser, optical, range reducedBluetooth, cable connection, etc.

The processor 34 executes instructions that cause the device 24 tobehave in a predetermined manner. The instructions may be written usingone or more programming languages, scripting languages, assemblylanguages, etc. Additionally, the instructions may be carried out by aspecial purpose computer, logic circuits, or hardware circuits. Thus,the processor 34 may be implemented in hardware, firmware, software, orany combination of these methods. The term “execution” is the process ofrunning a program or the carrying out of the operation called for by aninstruction. The processor 34 executes an instruction, meaning that itperforms the operations called for by that instruction. The processor 34couples to the communication interface 32.

The processor 34 may retrieve a set of instructions from a permanentmemory device and copy the instructions in an executable form to atemporary memory device. The temporary memory device is generally someform of random access memory (RAM). The data in RAM is volatile meaningthat it remains only as long as the device is turned on. When the deviceis turned off, RAM loses its data. Read only memory (ROM) refers tospecial memory used to store programs that boot the device and performdiagnostics. The values stored in ROM are always there, whether thepower is on or not. For this reason, it is called non-volatile memory.Flash memory is a type of constantly-powered nonvolatile memory that canbe erased and reprogrammed in units of memory called blocks.

The memory 36 stores the device service description 38. The device mayhave a plurality of memories 36 using different memory technologiesincluding, but not limited to, RAM, ROM, flash memory, etc. The memorymay include a cache. The cache may include, but is not limited to, adedicated bank of high-speed memory or a reserved section of regularmemory used to improve performance. The cache provides a temporarystorage area for instructions and data.

The device service description 38 may be a file or web browser pagewritten in XML format. The XML formatted file or page includesinformation about the device 24 and the services that the device 24provides. In an exemplary embodiment, the device service description 38includes context information for the device 24. The context informationmay include, but is not limited to, a geographic location of the device24. The context information provides additional information relative tothe services provided by the device 24. For example, if the device 24 isa camera, the camera may store context information for each photographtaken by the camera that includes, but is not limited to, a date thephotograph is taken, a time the photograph is taken, a location at whichthe photograph is taken, a subject matter of the photograph, atemperature at the photograph location, a photographer, etc. The cameramay store context information describing the context information storedfor each picture and/or may store context information related to thecamera itself. Context information related to the camera itself may bethe geographic location of the camera, a status of the camera battery, atotal memory size of a camera memory, a remaining memory size of thecamera memory, etc. Context information is also saved relative to eachphotograph which is an item stored at the camera.

The control point device 26 may send a request to the camera requestingthe device service description 38 that includes the context informationrelated to the camera itself. In this example, the response includes thecontext information in the device service description 38. Based on thisinformation, the control point device 26 may send a request to thecamera to send the control point device 26 all of the pictures taken onAug. 6, 2004. The control point device 26 “discovered” that the camerasaved the date information associated with each photograph, and thus,could request the service of getting the photographs based on the datecontext information. In this example, the request from the control pointdevice 26 includes the context information and the device 24 performsthe service based on the context information included with the request.In an alternative embodiment, the device 24 that is a camera may receivea request from the control point device 26 that does not include contextinformation. For example, the control point device 26 sends a requestfor a list of photographs at the device 24. The device 24 responds withthe list of photographs at the device 24 with the list of picturesincluding the context information associated with each photograph. Inthis example, the response includes the context information with theresponse.

With reference to FIG. 3, the control point device 26 comprises adisplay 40, a communication interface 42, and a processor 44. Differentand additional components may be incorporated into the device 26. Thedisplay 40 of the device 26 is optional. The display 40 presentsinformation to a user. The display 40 may be a TFT display, an LEDdisplay, an LCD, or any of a variety of different displays known tothose skilled in the art.

The communication interface 42 provides an interface for receiving andtransmitting calls, messages, and any other information communicablebetween devices. Communications between the control point device 26 andother control point devices 26, and/or to devices 24 may be through oneor more of the following connection methods, without limitation: aninfrared communications link, a wireless communications link, a cellularnetwork link, a link established according to TCP/IP, etc. Transferringcontent to and from the control point device 26 may be through one ormore of these connection methods. The control point device 26 maycommunicate using various transmission technologies including, but notlimited to, CDMA, GSM, UMTS, TDMA, TCP/IP, Bluetooth, IrDA, RFID, etc.The control point device 26 may communicate using various mediaincluding, but not limited to, radio, infrared, laser, optical, rangereduced Bluetooth, cable connection, etc.

The processor 44 executes instructions that cause the device 26 tobehave in a predetermined manner. The instructions may be written usingone or more programming languages, scripting languages, assemblylanguages, etc. Additionally, the instructions may be carried out by aspecial purpose computer, logic circuits, or hardware circuits. Thus,the processor 44 may be implemented in hardware, firmware, software, orany combination of these methods. The processor 44 executes aninstruction, meaning that it performs the operations called for by thatinstruction. The processor 44 couples to the communication interface 42.

With reference to FIG. 4, an exemplary message sequence between thecontrol point device 26 and the device 24 is shown. The communicationinterface 42 of the control point device 26 sends an HTTP Get Request 50to the device 24 to retrieve the device service description 38 from thedevice 24. The communication interface 32 of the device 24 receives theHTTP Get Request 50 from the control point device 26. The processor 34of the device 24 processes the received HTTP Get Request 50 and selectsthe device service description 38 from the memory 36. The processor 34of the device 24 creates an HTTP Get Response 52 that includes thedevice service description. The communication interface 32 of the device24 sends the HTTP Get Response 52 to the control point device 26. Thecommunication interface 42 of the control point 26 receives the HTTP GetResponse 52 including the device service description 38. The processor44 of the control point device 26 processes the received HTTP GetResponse 52 and selects the device 24 to perform a service for thecontrol point device 26 based, for example, on the geographic locationof the device 24 included in the device service description 38 and/orany other the context information of the device 24 included in thedevice service description 38. The message format may be, but is notlimited to, SSDP or SOAP.

FIG. 5 shows an example use case of the system 2. The network 4 includesthe cellular telephone 6, the PC 12, and the video camera 22. Thecellular telephone 6 may be the example control point device 26. The PC12 and the video camera 22 may be example devices 24. The cellulartelephone 6 sends an HTTP Get Request 60 to the PC 12 to retrieve adevice service description from the PC 12. Similarly, the cellulartelephone 6 sends an HTTP Get Request 62 to the video camera 22 toretrieve a device service description from the video camera 22. The PC12 creates an HTTP Get Response 64 that includes the device servicedescription of the PC 12 and sends the HTTP Get Response 64 to thecellular telephone 6. Similarly, the video camera 22 creates an HTTP GetResponse 66 that includes the device service description of the videocamera 22 and sends the HTTP Get Response 66 to the cellular telephone6.

The cellular telephone 6 selects the video camera 22 to perform servicerequest 68 by pointing the cellular telephone 6 at the video camera 22and selecting the video camera 22 based on the geographic locationinformation contained in the context information include in the deviceservice description of the video camera 22. The cellular telephone 6 mayuse a local compass or other similar sensor to determine the pointingdirection of the cellular telephone 6 to the video camera 22. Thecellular telephone 6 and/or the video camera 22 may use, for example, aglobal positioning system to determine the geographic location of thecellular telephone 6 and the video camera 22 respectively as known tothose skilled in the art.

Service request 68 may be a request that the video camera 22 send avideo clip taken at a specified time on a specified date to the cellulartelephone 6 using the context information included with the servicerequest 68. Similarly, the cellular telephone 6 selects the PC 12 toperform service request 70 by pointing the cellular telephone 6 at thePC 12 and selecting the PC 12 based on the geographic locationinformation contained in the device service description of the PC 12.The cellular telephone 6 may use a local compass or other similar sensorto identify the PC 12 using the pointing direction of the cellulartelephone 6. Service request 70 may be a request that the PC 12 copy thespecified video clip sent through the cellular telephone 6.

Additionally, a control point device 26 may search for services based onthe ability of the device 24 to support the use of context informationinstead of based on the context information itself. For example, acamera may attempt to locate a content directory service that supportsthe use of context information. The content directory service may storethe content of items and/or containers and provide browsing andsearching for the items and/or the containers. The camera providescontext information with each photograph, and thus, requests a contentdirectory service that also supports use of the context information.

Context information may include usage history that lists each user usingthe device and/or service, when the device and/or service is used, whatcontrol point is used to request the service, etc. Context triggeredmessages may be initiated from the device such as reminders ornotifications based on the context information that the device stores.Thus, messages also may be initiated from the device 24 to the controlpoint device 26.

It is understood that the invention is not confined to the particularembodiments set forth herein as illustrative, but embraces all suchmodifications, combinations, and permutations as come within the scopeof the following claims. Thus, the description of the preferredembodiments is for purposes of illustration and not limitation.

What is claimed is:
 1. A method comprising: retrieving a first deviceservice description contained in a first file from a first device usinga universal plug and play network, the first device service descriptioncomprising information about the first device and the services providedby the first device, and further comprising information associated witha second file containing context information, the context informationcomprising additional information of at least one of the first device,the services provided by the first device, and one or more items relatedto the first device; and selecting the first device to perform a firstservice for a second device based on the context information in thefirst device service description by pointing the second device at thefirst device; retrieving a second device service description containedin a third file from a third device using the universal plug and playnetwork, the second device service description including informationassociated with a fourth file containing context information of thethird device; and selecting the third device to perform a second servicerelated to the first service for the second device based on the contextinformation of the third device included in the second device servicedescription by pointing the second device at the third device, thesecond service involving a copy action, wherein the copy actioncomprises selecting an item in a display at the second device whilepointing the second device at the first device, and releasing the itemin the display at the second device while pointing the second device atthe third device, thereby copying the item from the first device to thethird device.
 2. The method of claim 1, wherein the context informationof the first device comprises a geographic location of the first device.3. The method of claim 2, wherein selecting the first device to performthe first service for the second device further comprises: determining ageographic location of the second device; determining a pointingdirection to the first device from the second device; and selecting thefirst device based on the pointing direction to the first device fromthe second device, the geographic location of the first device, and thegeographic location of the second device.
 4. The method of claim 1,wherein the context information of the third device includes ageographic location of the third device.
 5. The method of claim 4,wherein selecting the third device to perform the second service for thesecond device further comprises: determining a pointing direction to thethird device from the second device; and identifying the third devicebased on the pointing direction to the third device from the seconddevice, the geographic location of the third device, and the geographiclocation of the second device.